Rhodium-catalyzed hydrogenation of unsaturated aldehydes to unsaturated

Abstract

Process for selective hydrogenation of aliphatic unsaturated aldehyde to unsaturated alcohol with gaseous hydrogen using supported rhodium-complex catalyst. This invention relates to a process for preparing unsaturated aliphatic alcohols wherein unsaturated aliphatic aldehydes are selectively hydrogenated using supported rhodium-complex catalyst. Unsaturated alcohols have use in the production of plastics and perfumes. Crotonyl alcohol, for example, has utility for the production of copolymers with vinyl acetate or styrene, and also as an intermediate for synthesis of other organic compounds. Allyl alcohol is a precursor for butanediol which is used to produce tetrahydrofuran, polyesters such as polybutylene terephthalate, and polybutylene oxide based polyurethanes. Particular difficulty in selectively hydrogenating alpha, beta unsaturated aldehydes is described in U.S. Pat. No. 3,655,777 (Rylander et al., 1972, assigned to Engelhard Minerals and Chemicals) wherein patentees teach many catalysts, e.g., palladium, platinum, rhodium, ruthenium, and nickel, usually reduce the double bond in preference over reduction of the carbonyl group. Rylander also teaches a high pressure process to obtain unsaturated alcohols using an osmium catalyst.